[Development report #1] Audio Stack Improvements

The past (and first) week working on the audio stack, sponsored by the
FreeBSD Foundation, I:

- Set up my development environment; a VM image running -CURRENT in
  bhyve with PCI-passthru enabled to do all of the driver (kernel
  generallly) development in the VM.
- Wrote a small series of patches for vmrun.sh:
  https://reviews.freebsd.org/D43269
  https://reviews.freebsd.org/D43270
- Modified the snd_uaudio(4) driver to provide information about the
  sound card (manufacturer, model and attached driver), as opposed to
  the current generic "USB Audio" string, so /dev/sndstat and programs
  like mixer(8) can output more useful information about USB audio
  devices.
  https://reviews.freebsd.org/D43347
- Submitted a patch to update (and unify) the description format for all
  sound devices, since some of them haven't been touched for years.
  https://reviews.freebsd.org/D43349
- Implemented device_set_descf() , a printf-like version of
  device_set_desc().
  https://reviews.freebsd.org/D43370
- Was preparing a few more smaller patches.
- Started looking into possible solutions to
  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=194727
  also mentioned in the first paragraph of the BUGS section of the
  snd_uaudio(4) man page.

Christos